Network Diagnostics Toolkit

A complete network troubleshooting reference for agents and developers. Covers 9 diagnostic workflows using standard Unix tools (ping, dig, curl, openssl, traceroute, netcat, ss) available on any macOS/Linux system. No API keys or external services required.

Includes:

• Quick symptom-to-diagnosis lookup table (connection refused, timeout, SSL errors, slow response)
• DNS resolution and propagation checks across multiple resolvers
• SSL/TLS certificate inspection: expiry, chain, cipher suites, protocol version
• Port accessibility testing for common services (HTTP, HTTPS, SSH, databases)
• HTTP timing breakdown: DNS lookup, TCP connect, TLS handshake, TTFB, total time
• Traceroute and MTR for network path analysis and latency isolation
• Firewall and security group verification
• Continuous monitoring patterns with alerting
• Three real-world diagnostic scenarios with step-by-step resolution
• Decision tree for systematic troubleshooting
• Standardized diagnostic report format

Every command includes interpretation guidance - not just what to run, but what the output means and what to do about it. Built from real production debugging experience.